The present invention deals with catheters. More specifically, the present invention deals with delivery of a small bolus of liquid with a catheter.
A wide variety of different mechanisms and techniques have been developed in order to treat coronary disease. However, such techniques and devices are typically drawn to the physical manipulation of biological tissues, such as heart tissue, or other vascular tissue within the vascular system.
For example, some treatment techniques are drawn to the physical removal or dilation of restrictions (stenoses and total occlusions) in the vasculature. Techniques for dealing with this type of disease have included percutaneous transluminal coronary angioplasty (PTCA) in which an angioplasty balloon catheter is inserted into the body via the femoral artery and positioned across a restriction in an artery. The balloon is inflated to widen the restriction and restore blood flow to portions of the heart muscle previously deprived of oxygenated blood. Implantation of stents using PTCA is also a common technique for opening an arterial restriction.
Another technique for dealing with vascular disease includes coronary artery bypass graft (CABG) procedures. Such procedures typically include the placement of a graft at a desired location in the vasculature to supplement blood flow to the area previously deprived of blood for (or provided with reduced blood flow) due to the vascular restriction. One common type of CABG procedure involves placement of a sapphenous vein graft (SVG) between the ascending aorta proximal of the restriction, and a region in the restricted vessel distal of the restriction.
Another technique for dealing with vascular disease includes an atherectomy procedure. In an atherectomy procedure, an atherectomy device is placed in the vasculature proximate the restriction. The atherectomy device is deployed to physically cut away, abrade, or otherwise physically remove, the occlusive material from the restricted vessel. The portions of the restriction which are severed by the atherectomy device are subsequently removed by aspiration, or by another suitable device.
Another technique called transluminal myocardial revascularization is also receiving attention in the medical community as an acceptable therapy.
Various drug therapies have also been developed. Such therapies have been used in place of, and in conjunction with, the above mentioned therapies under certain circumstances. For example, during grafting procedures, it may be desirable to deliver drugs to the graft site which inhibit the formation of thrombus. In addition, some drug therapies have been developed which involve the delivery of drugs directly to the heart tissue. With recent advancements in the pharmaceutical industry, other drug therapies have also become desirable. Some such recent pharmaceutical developments include the development of gene therapy drugs, such as growth factors.
A transluminal technique for delivering the drugs, along with the various types of known positioning and visualization techniques commonly used with transluminal treatments, can be highly desirable. The drug therapies typically require site specific administration of the drug. Transluminal techniques can be effectively used to deliver a liquid material to a selected site in the vasculature.
However, drug therapies, can be prohibitively expensive. For example, newly developed drugs are commonly extremely expensive and can only be administered in any pragmatic fashion in very low volumes. Typically, such drugs only need to be administered to the vascular site being treated. However, there is no technique available to date by which the site to be treated can be accessed transluminally with a catheter and which enables only a very small quantity of drug to be delivered from the distal tip of the catheter to the treatment site.
Rather, conventional transluminal drug delivery catheters require a proximal infusion device which is connected to a proximal end of the infusion catheter and which is used to pressurize a fluid or infusate which contains the drug to be delivered. The catheter is filled with the infusate and the drug is administered at the distal tip of the infusion catheter (upon pressurization of the infusate) after the catheter is inserted and properly positioned. While the internal volume of such infusion catheters is typically small, it is still much too large to make drug delivery with extremely expensive drugs practical.